Circuit board and packaged chip

ABSTRACT

A circuit board includes an upper circuit and a lower surface that are opposite to each other, a plurality of heat sink bonding pads, and a plurality of heat sink conductive pads. The heat sink bonding pads are disposed on the upper surface and electrically insulated from one another, and are used to electrically connect to a heat sink. The heat sink conductive pads are disposed on the lower surface, electrically insulated from one another, and electrically connected to the heat sink bonding pads, respectively.

This application is a Continuation of pending U.S. application Ser. No.15/850,376, filed on Dec. 21, 2017, which claims the benefit of Taiwanapplication Serial No. 106125479, filed Jul. 28, 2017, the subjectmatter of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates in general to a circuit board and a packaged chip,and more particularly to a circuit board and a packaged chip in which anelectrical connection between a heat sink and the circuit board can betested through an electrical signal.

Description of the Related Art

With the evolution and development of electronic products, electronicproducts have become indispensables in the modern world. Among manydevices, chips are extensively applied in electronic products. During anoperation of a chip, heat is inevitably produced, raising thetemperature of the chip. To prevent the operation of the chip fromeffects of high temperatures, a heat sink, for example, is usuallyprovided in a packaged chip. However, given an unsatisfactory adhesioncondition of a heat sink, a so-called antenna effect may be resulted;that is, one end of the heat sink with the unsatisfactory adhesioncondition may receive external electromagnetic signals that interferethe operation of the chip, or may transmit electromagnetic signals thataffect other devices.

SUMMARY OF THE INVENTION

It is one object of the present invention to provide a circuit board anda packaged chip. A plurality of heat sink bonding pads and a pluralityof heat sink conductive pads are electrically connected through aplurality of heat sink traces that are insulated from one another in thecircuit board, respectively, so as to identify a packaged chip includinga heat sink with an unsatisfactory adhesion condition.

According to an embodiment of the present invention, a circuit boardincludes an upper surface and a lower surface that are opposite to eachother, a plurality of heat sink bonding pads, and a plurality of heatsink conductive pads. The heat sink bonding pads are disposed on theupper surface, electrically insulated from one another, and are used toelectrically connect to a heat sink The heat sink conductive pads aredisposed on the lower surface, electrically insulated from one another,and electrically connected to the heat sink bonding pads, respectively.

According to another embodiment of the present invention, a packagedchip includes a circuit board and a heat sink. The heat sink is adheredon heat sink bonding pads of the circuit board, and is electricallyconnected to the heat sink bonding pads. The heat sink bonding pads areelectrically to one another through the heat sink.

The above and other aspects of the invention will become betterunderstood with regard to the following detailed description of theembodiments. The following description is made with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a section view of a circuit board according to an embodimentof the present invention;

FIG. 2 is a top view of a packaged chip according to an embodiment ofthe present invention;

FIG. 3 is a section view of a packaged chip along a section line A-A′ inFIG. 2;

FIG. 4 is a section view of a packaged chip along a section line B-B′ inFIG. 2; and

FIG. 5 is a top view of a heat sink according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

For one skilled in the art to better understand the present invention,constituents and expected effects of the present invention are describedin detail in the embodiments with the accompanying drawings below.Modifications based on different perspectives and applications may bemade to the details of the disclosure without departing from the spiritof the present invention. It should be noted that, the drawings aresimplified diagrams for illustrative purposes, and are not to beconstrued as limitations to the fundamental concept of the presentinvention. The drawings depict only elements associated with the presentinvention, and are not drawn to actual numbers, shapes and sizes of theelements in applications. In actual applications, the numbers, shapesand sizes of these elements may be modified based on actual applicationrequirements, and a layout of these elements may be more complex.

FIG. 1 shows a section view of a circuit board according to anembodiment of the present invention. As shown in FIG. 1, a circuit board100 of the embodiment includes an upper surface 100 a and a lowersurface 100 b that are opposite to each other, a circuit layer 110, aplurality of heat sink bonding pads HBP and a plurality of chip bondingpads CBP1 and CBP2 disposed on the upper surface 100 a of the circuitboard 100, and a plurality of heat sink conductive pads HP and aplurality of chip conductive pads CP1 and CP2 disposed on the lowersurface 100 b of the circuit board 100.

The circuit layer 110 may include an insulation layer 112, a pluralityof heat sink traces TRH, and a plurality of chip traces TRC1 and TRC2.The heat sink traces TRH and the chip traces TRC1 and TRC2 are disposedin the insulation layer 112, so as to allow the heat sink traces TRH andthe chip traces TRC1 and TRC2 to be electrically insulated from oneanother through the isolation of the insulation layer 112. It is commongeneral knowledge to one person skilled in the art that, the heat sinktraces TRH and the chip traces TRC1 and TRC2 may be formed throughmultiple insulation layers and multiple conductive line layers, andconductive wires of different conductive wire layers may be electricallyconnected in a vertical direction through vias of the insulation layers.Thus, associated details are omitted herein.

The heat sink bonding pads HBP are for electrically connecting to a heatsink device (e.g., a heat sink), and are electrically insulated from oneanother. Further, the heat sink bonding pads HBP are electricallyinsulated from the chip bonding pads CBP1 and CBP2. That is, given thatthe circuit board 100 is not yet provided with electronic devices orheat sinks thereon, each heat sink bonding pad HBP is not electricallyconnected to another heat sink bonding pad HBP or any of the chipbonding pads CBP1 and CBP2. The heat sink bonding pads HBP may beelectrically connected to the heat sink conductive pads HP through theheat sink traces TRH in the circuit layer 110, respectively. That is,given that the circuit board 100 is not yet provided with electronicdevices or heat sinks thereon, each heat sink bonding pad HBP iselectrically connected to one heat sink conductive pad HP through onlyone heat sink trace TRH, and is not electrically connected to the chipconductive pads CP1 and CP2. The heat sink conductive pads HP areelectrically insulated from one another, and are further electricallyinsulated from the chip conductive pads CP1 and CP2. That is, given thatthe circuit board 100 is not yet provided with electronic devices orheat sinks thereon, each heat sink conductive pad HP is not electricallyconnected to another heat sink conductive pad HP or any of the chipconductive pads CP1 and CP2. The heat sink conductive pads HP are forelectrically connecting to an external ground terminal.

The chip bonding pads CBP1 and CBP2 are for electrically connecting toan electronic device (e.g., a chip). The chip bonding pads CBP1 may beused to electrically connect to a ground terminal of an electronicdevice, and may be, without electrically connecting to the heat sinkconductive pads HP, electrically connected to at least one of the chipconductive pads CP1 through the chip traces TRC1 in the circuit layer110. For example, the chip bonding pad CBP1 may be electricallyconnected to two chip conductive pads CP1. The chip conductive pads CP1are for electrically connecting to an external ground terminal. The chipbonding pads CBP2 are for electrically connecting to a non-groundterminal (e.g., other voltage signal terminals) of the electronicdevice, and may be electrically connected to one chip conductive pad CP2through the chip trace TRC2 in the circuit layer 110. The chipconductive pads CP2 are for electrically connecting to an externalnon-ground terminal (e.g., a voltage signal). It should be noted that,the electrical connections between the chip bonding pads CBP1 and CBP2and the chip conductive pads CP1 and CP2 are not limited to the aboveexamples. In other embodiments, the electrical connections between thechip bonding pads CBP1 and CBP2 and the chip conductive pads CP1 and CP2may be designed based on actual requirements.

FIG. 2 shows a top view of a packaged chip 200 according to anembodiment of the present invention. FIG. 3 shows a section view of thepackaged chip 200 along a section line A-A′ in FIG. 2. FIG. 4 shows asection view of the packaged chip 200 along a section line B-B′ in FIG.2. As shown in FIG. 2 and FIG. 3, the packaged chip 200 of theembodiment includes a circuit board 100, a heat sink 210, a chip 220, ametal wire 230, a packaging glue 240 and a solder ball 250. Thestructure of the circuit board 100 may be referred from the abovedescription, and shall be omitted herein for brevity.

The heat sink 210 is electrically connected to the heat sink bonding padHPB of the circuit board 100 through an adhesive agent (e.g., aconductive glue). The heat sink 210, in a top view direction Z of thecircuit board 200, covers the chip 200, and an upper surface of the heatsink 210 is revealed outside the packaging glue 240, so as to dissipateheat that is generated by the chip 220 in operation. Because the heatsink 210 includes a conductive material (e.g., metal) having good heatdissipation, the heat sink 210 additionally provides an electromagneticinterference (EMI) protection effect for blocking the chip 220 frominterference of external signals.

FIG. 5 shows a top view of the heat sink 210 according to an embodimentof the present invention. The heat sink 210 includes four pins 210 b,which are respectively adhered on the four heat sink pads HBP on thecircuit board 100 to electrically connect the heat sink 210 to a groundterminal through the four heat sink conductive pads HP, as shown in FIG.2 and FIG. 3. Further, each of the pins 210 b may have an opening 212 toaccordingly reduce the possibility of breaking the pins 210 b aftermultiple expansions and contractions. It should be noted that, thenumber of the pins 210 b is not limited to four. In another embodiment,the number of the pins 210 b is eight. In this situation, the circuitboard 100 correspondingly includes eight heat sink bonding pads HBP andeight heat sink conductive pads HP. It should be noted that, the numberof the pins 210 b of the present invention is not limited to being aneven number.

The chip 220 may be electrically connected to the chip bonding pad CBPon the circuit board 100. In this embodiment, a solder pad of the chip220 is electrically connected to the chip bonding pads CBP1 and CBP2 by,for example but not limited to, wire bonding. In an alternativeembodiment, the solder pad may also be electrically connected to thechip bonding pads CBP1 and CBP2 by flip-chip or other methods.

The heat sink 210 is provided with the packaging glue 240 at both itsinterior and exterior, and the packaging glue 240 covers the chip 220.In another embodiment, the packaging glue is provided only at theinterior of the heat sink. In another embodiment, the packaged chip mayexclude the packaging glue.

The solder ball 250 is connected to the heat sink conductive pads HP andthe chip conductive pads CP1 and CP2 to increase the rate ofsuccessfully joining the packaged chip 200 with other circuit boards. Inanother embodiment, the packaged chip may also exclude the solder ball.

It should be noted that, in a conventional packaged chip, the groundtraces connected to the heat sink conductive pads are electricallyconnected to one another. In this situation, even if the adhesionbetween the pins of the heat sink and the heat sink bonding pads isunsatisfactory, a heat sink conductive pad may still be electricallyconnected to other heat sink conductive pads via the ground traces. As aresult, whether the pins of the heat sink and the heat sink bonding padsare adhered poorly cannot be determined based on a resistance valuebetween two heat sink conductive pads, and so a packaged chip with anantenna effect cannot be identified.

However, in the present invention, when the heat sink 210 is not yetadhered to the circuit board 100, the heat sink conductive pads HP areelectrically insulated from one another. When the heat sink 210 isadhered to the circuit board 100, the heat sink conductive pads HPoriginally electrically insulated from one another in the circuit board100 can electrically connect to the heat sink 210 through the respectiveheat sink traces TRH to further electrically connect to one anotherthrough the heat sink 210. Thus, when the pins 210 b of the heat sink210 and the heat sink bonding pads HBP are poorly adhered, theresistance values between the corresponding heat sink conductive pad HPand other heat sink conductive pads HP are significantly increased. Assuch, the resistance value between two heat sink conductive pads HP canbe measured to determine whether a situation where the pins 210 b of theheat sink 210 and the heat sink bonding pads HBP are poorly adheredexists, so as to further identify a packaged chip with an antennaeffect. For example, when the resistance value between any two heat sinkconductive pads does not fall within a predetermined range, it meansthat the pins of the heat sink and the heat sink bonding pads are poorlyadhered, and the packaged chip has an antenna effect and is thusdetermined as a defective product.

While the invention has been described by way of example and in terms ofthe embodiments, it is to be understood that the invention is notlimited thereto. On the contrary, it is intended to cover variousmodifications and similar arrangements and procedures, and the scope ofthe appended claims therefore should be accorded the broadestinterpretation so as to encompass all such modifications and similararrangements and procedures.

What is claimed is:
 1. A circuit board, comprising: an upper surface anda lower surface that are opposite to each other; a heat sink bondingpad, disposed on the upper surface and for electrically connecting to aheat sink; a chip bonding pad, disposed on the upper surface and forelectrically connected to an electronic device; and a heat sinkconductive pad, disposed on the lower surface, and electricallyconnected to the heat sink bonding pad, wherein the heat sink bondingpad is electrically isolated to the chip bonding pad.
 2. The circuitboard according to claim 1, further comprising: a circuit layer,comprising a heat sink trace, wherein the heat sink conductive pad areelectrically connected to the heat sink bonding pad through the heattrace.
 3. The circuit board according to claim 2, further comprising: achip conductive pad, disposed on the lower surface, and electricallyisolated to the heat sink conductive pad.
 4. The circuit board accordingto claim 3, wherein the circuit layer further comprises: a chip trace,wherein the chip conductive pad is connected to the chip bonding padsthrough the chip trace.
 6. The circuit board according to claim 1,further comprising: a metal wire, wherein the chip bonding pad iselectrically connected to the electronic device through the metal wire.7. The circuit board according to claim 1, wherein the heat sinkcomprises a pin having an opening.
 8. The circuit board according toclaim 7, wherein the heat sink bonding pad is electrically connected tothe heat sink through the pin.
 9. A chip package, comprising: anelectronic device; and a circuit board, wherein the electronic device isdisposed on the circuit board, the circuit board comprises: an uppersurface and a lower surface that are opposite to each other; a heat sinkbonding pad, disposed on the upper surface and for electricallyconnecting to a heat sink; a chip bonding pad, disposed on the uppersurface and for electrically connected to the electronic device; and aheat sink conductive pad, disposed on the lower surface and electricallyconnected to the heat sink bonding pad, wherein the heat sink bondingpad is electrically isolated to the chip bonding pad.
 10. The chippackage according to claim 9, wherein the electronic device is disposedbetween the circuit board and the heat sink.
 11. The chip packageaccording to claim 9, wherein the circuit board further comprises acircuit layer, the circuit layer comprises a heat sink trace, whereinthe heat sink conductive pad is electrically connected to the heat sinkbonding pad through the heat trace.
 12. The chip package according toclaim 9, wherein the heat sink comprises a pin having an opening. 13.The chip package according to claim 12, wherein the heat sink bondingpad is electrically connected to the heat sink through the pin.
 14. Thechip package according to claim 9, further comprising: a metal wire,wherein the chip bonding pad electrically connected to the electronicdevice through the metal wire.
 15. A chip package, comprising: anelectronic device; and a circuit board, wherein the electronic device isdisposed on the circuit board, the circuit board comprises: an uppersurface and a lower surface that are opposite to each other; a heat sinkbonding pad, disposed on the upper surface and for electricallyconnecting to a heat sink; a chip bonding pad, disposed on the uppersurface and for electrically connected to the electronic device; and acircuit layer, comprises at least a heat sink trace and a chip trace,and the heat sink trace is electrically isolated to the chip trace,wherein the heat sink bonding pad and the chip bonding pad areelectrically connected to the heat sink trace and the chip trace,respectively.
 16. The chip package according to claim 15, furthercomprising: a heat sink conductive pad and a chip conductive pad,disposed on the lower surface and electrically connected to the heatsink trace and the chip trace, respectively.
 17. The chip packageaccording to claim 15, wherein the heat sink comprises a pin having anopening, and the heat sink bonding pad is electrically connected to theheat sink through the pin.
 18. The chip package according to claim 15,further comprising: a packaging glue, disposed on the circuit board. 19.The chip package according to claim 16, wherein a first part of the heatsink is covered by the packaging glue and a second part of the heat sinkis not covered by the packaging glue.
 20. The chip package according toclaim 15, further comprising: a solder ball, connected to the heat sinkconductive pad.